The North American Repository for Archaeological Isotopes – Scientific Data

The North American Repository for Archaeological Isotopes (NARIA) stands as the foremost collection of isotopic measurements available openly, with a vast compilation of 28,374 data entries derived from bioarchaeological specimens across North America—encompassing Canada, Greenland, Mexico, and the United States of America. This extensive dataset chronicles over 12,000 years of history. It incorporates measurements of stable isotopes like δ13C, δ15N, δ18O, and radiogenic isotopes such as 87Sr/86Sr from archaeological samples, including human, animal, and plant sources, alongside their accompanying contextual data such as location, chronology, and cultural affiliations.

The collation of these isotopic assessments, along with additional data forms, presents a significant opportunity for research into ancient human societies. Areas of study that particularly benefit include the understanding of past human mobility, environmental conditions, and dietary practices. This collection not only brings to light spatial and temporal data gaps but also provides direction for the focus of future research endeavors.

The application of stable isotope analysis in environmental science, chemistry, and geology is well-established, but it first found its archaeological footing in the studies of Vogel and van der Merwe in the 1970s. Their work utilized stable carbon isotope analysis to understand maize consumption in a prehistoric group from the northeastern woodlands, an area that is modern-day New York state. By examining the differential isotope signatures between C3 plants, like many from temperate regions, and C4 plants, such as maize from tropical or arid areas, they uncovered insights into dietary patterns. This foundational research laid the groundwork for over 40 years of isotopic investigations in North American archaeology.

Early research largely centered on paleodietary reconstructions, probing the proliferation and dietary integration of maize and its cultural ramifications among prehistoric societies. Other studies expanded the scope to explore human reliance on marine versus terrestrial resources or the debate between plant and animal protein sources. These inquiries primarily employed δ13C and δ15N measurements, with subsequent ventures harnessing Sr isotope analysis to delve into dietary and migratory phenomena.

As these studies evolved, they encountered challenges like the dietary routing into various tissues and fractionation effects, spurring interest in issues of isotopic preservation and diagenetic alteration from variables such as temperature and pH. This led to a longstanding series of experimental feeding studies. At the same time, advancements made strontium isotope analysis a powerful proxy for tracing geological origins during tissue formation, a process examined through a multitude of experimental setups.

In recent decades, isotopic research has greatly diversified, tackling topics such as paleodiet reconstruction, human movement patterns, animal husbandry, and the environmental contexts of bygone eras. Innovative techniques like continuous flow mass spectrometry, paired with methodological advancements in sample preparation and data standardization, have made isotope analysis increasingly accessible and cost-effective.

Enhanced datasets, now more representative and comprehensive in contextual information, are crucial for scientific rigor, allowing researchers to evaluate data quality. These advancements accentuate the need for modern, locally pertinent baseline data to deepen the understanding of isotope proxies. Extensive curated datasets can address these requirements, empowering researchers to explore diet, environment, and mobility questions over myriad scales and identify research lacunae for future inquiry.

Despite the abundance of isotopic measurements from North American archaeological contexts, a central open-access repository for such data was notably absent until now. NARIA fulfills this role as a partner of the IsoMemo network, compiling a vast array of previously reported isotopic data on both human and animal tissues—such as bone collagen, bone bioapatite, tooth enamel bioapatite, and tooth dentin collagen—alongside plant material from archaeological contexts across North America.

This resource not only aggregates human and animal isotope values with comprehensive metadata but also incorporates plant data from archaeological settings, supplemented by modern sources when necessary. This extensive dataset provides a holistic overview of isotopic measurements across temporal spans and various materials, offering insights into the progression and focus of isotopic research over the years.

The structural information provided by NARIA includes a detailed breakdown of isotope measurement distributions over time, category-specific data proportions—whether human, animal, or plant in origin—and analyses of scholarly publications contributing to the dataset. This database is an invaluable tool for ongoing and future isotopic research in archaeology.